moy-fp/test/Function/tap.test.js

A functional programming library.

import __ from '../../src/Function/__'
/**
 * (a -> *) -> a -> a
 */
import tap from '../../src/Function/tap'

test('tap(not using __)', () => {
  expect(
    tap(x => x + 1)(1)
  ).toBe(1)
})

test('tap(using __)', () => {
  expect(
    tap(__, 1)(x => x + 1)
  ).toBe(1)
})